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چکیده
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Objectives: Dicalcium phosphate (DCP) is considered the most important phosphate product in livestock and poultry nutrition and provides more than 85% of the mineral phosphorus required by poultry. But in last forty years, losses due to leg abnormalities that occur at the end of breeding period have been one of the major problems of country's poultry breeding industry. This abnormality causes the removal of a significant part at the end of breeding period. Therefore, the aim of present experiment was to find out whether use of organic DCP can improve properties of broiler chicken bones compared to inorganic DCP. Materials & Methods: Experiment was conducted in a completely randomized design with 7 treatments, 4 replications and 10 male broiler chickens of Ross308 in each replication. Treatments included seven types of experimental feed for each of starter, grower and finisher. Phosphorus from two sources of phosphorus supply (DCP with inorganic source and DCP with organic source), at three levels (0.15, 0.30 and 0.45), added to the basal diet containing 0.15 phosphorus. At the end of 7, 14, 21 and 35 days of age, number chickens with rickets in each experimental unit was counted. At 35 days old, after blood sampling, tibia bones of right and left legs of two killed chickens from each experimental unit were separated. Then, parameters of length, diameter, strength, percentage of ash and phosphorus of tibia bones, as well as serum alkaline phosphatase were measured. Data were statistically analyzed using SAS software and GLM procedure. Duncan's test was used to compare the differences between means. Results & Conclusion: Results of 35 days showed that in chickens receiving basal diet, serum alkaline phosphatase was lower, the length of tibia was shorter and strength of bone was weaker than other experimental groups (P<0.05). Chickens that received 0.30% phosphorus from organic DCP had shorter bone length than the same level of inorganic DCP (P<0.05). There was no sign
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